1. Field of the Invention
The present invention relates to an image retrieval system and method by which the image of a desired page is quickly retrieved from a specified document of a multiplicity of voluminous documents stored in a common memory for presentation on a display device.
2. Description of the Prior Art
In a video conference, in which a speaker discusses information with the aid of a displayed image of a page of a document provided on a video display, the overall system performance depends in part upon how quickly a desired page can be located among the myriad of pages and documents in the storage memory and selected for retrieval from the memory. Conventional systems of this kind use, for locating, selecting, and retrieving a desired page of a document, method (A) in which respective documents and pages are numbered and direct access is made to desired numbers and method (B) in which documents and pages are sequentially searched.
Method (A) has limitations in that it is difficult for the user to memorize, or search a list of, all of the names or descriptions of all of the documents and their corresponding page numbers. Method (B) has limitations in that the retrieval time can be relatively long and increases with the number of documents and their pages in memory.
A variety of alternative systems have been proposed for the retrieval of a document and its pages (in video image form), of which, method (C) produces an image frame displaying each page in a reduced size on one video image frame giving a user visual access to a number of pages simultaneously. Method (C) displays the retrieval image frame composed of the reduced size pages, for review and selection by the user. Method (C) is used in the DISCON 1000 Video Image Teleconferencing System manufactured by Interand Corporation, 3200 West Peterson Avenue, Chicago, Ill., 60659.
Method (D) displays one video image retrieval frame composed of a fraction of each page of a document (such as a corner) providing the user with visual reference to many pages of a document simultaneously. The fraction of each page of each document displayed is a function of the total area available for display of the retrieval frame and the total number of images to be displayed in the area.
Both methods (C) and (D) have limitations. Primarily, the memory space required for storing the retrieval frame for each page of each document is large for both methods (C) and (D). Additionally, the number of fractional pages which can be displayed on the retrieval frame, and still be easily read or recognized, is limited since the size of the fractional page images decreases with increasing numbers of pages in the document.
In summary, all of the above noted conventional retrieval methods, (A),(B),(C) and (D), are suitable only for retrieving a desired page from a relatively small number of documents of a few pages, but not for retrieving a specified page from a multiplicity of voluminous documents. In contrast, as discussed below, the present invention overcomes all of the foregoing disadvantages.